President Obama is probably not itching for a fight over abortion. But he might get one. With unusual speed, the Vatican has condemned Obama's Jan. 23 repeal of the ban on U.S. funding for foreign family-planning aid groups that offer abortion services.

The repeal fulfills a campaign promise Obama made to pro-choice supporters. But if the late-Friday-afternoon signing was an attempt to get the change in under the radar, it didn't work. Top Vatican officials, usually hesitant to respond directly to Washington's domestic-policy decisions, pounced quickly. By Saturday afternoon, the Holy See was e-mailing reporters the Sunday edition of its official daily, L'Osservatore Romano, which features a front-page headline describing Obama's decision as "very disappointing." (Read "Shhh. Obama Repeals the Abortion Gag Rule, Very Quietly.")

The same day, the secular Milan daily Corriere della Sera published an interview with a top Vatican official lashing out at the new U.S. President. Archbishop Rino Fisichella, head of the Pontifical Academy for Life, told the newspaper that the repeal of the abortion-funding ban was done with "the arrogance of those who, having power, think they can decide between life and death." Troubled by the swiftness of Obama's pro-choice move, Fisichella brushed off earlier vows by the new President to try to cut the number of abortions while ensuring a woman's access to the procedure. "On ethical questions, you can't play with words," said the Italian Archbishop, who is considered close to Pope Benedict XVI. "Hiding behind sophisms isn't worthy of he who has a responsibility towards citizens. People want clarity." (See pictures of Pope Benedict XVI visiting America.)

It's too early to predict a deep rupture in U.S.-Vatican relations. There was no mention of the issue in Sunday's regular Angelus ceremony, and the Pope personally sent warm messages of congratulations to Obama after both his election victory and the Inauguration. But don't count on Benedict staying silent as Obama ushers in more liberal laws for abortion or stem-cell research.

If he does speak out, the Pope is likely to use his representatives in America. The front-page Sunday story in L'Osservatore Romano focused on the U.S. bishops' response to the abortion-rights decree. A recent video advertisement being aired by Catholicvote.com puts Obama in the middle of the abortion debate, implying that the future President, an African American raised by a single mother, was himself at risk of being aborted.

Benedict knows that abortion is legal and widely available throughout the West, including virtually every country in Europe. It is the most glaring sign for the Pope of what he describes as the moral failings of contemporary life. But in the U.S., Benedict sees fertile possibility to challenge the status quo. On his trip to Washington and New York last April, Benedict heard how Catholics in America are being reinvigorated by a steady flow of more-traditional immigrant Catholic groups. That matters. Fisichella concluded his interview by saying, "What happens in the U.S. influences other parts of the world. For this [its leaders] must be capable of listening, having humility and maybe even asking others for help."

Obama won a majority of Catholic voters, in part because he was able to convince them that he was both the right man to lead the country and generally in tune with their values. In his public speeches and private diplomacy, Benedict will use his notable intellect to reaffirm for American Catholics what those values are. It would be a chance to influence abortion legislation both in the U.S. and around the world. On abortion, in other words, Benedict might be itching for a fight with Obama. If so, the new President will have to work hard to keep from getting bruised.